Insulation with tape adhering surface

ABSTRACT

Improved insulation segments (17) for fluid conduits (12) such as pipes and ducts, having a nontacky moisture resistant strip (60) which extends along edges (49) of the insulation which are adapted to be secured to other portions of the insulation, or to other insulation segments using a pressure sensitive, adhesive tape (80). This strip preferably comprises a cured adhesive which bonds to the paper or other surface to which it is applied which provides a good, dry, dirt free, smooth surface to which the pressure sensitive adhesive tape will strongly adhere.

FIELD OF THE INVENTION

This invention relates qenerally to insulation for use with fluidconduits such as pipes or ducts, and more particularly to sheets andseqments of such insulation which have been provided with a strip of amoisture resistant material for use with pressure sensitive adhesivetapes.

BACKGROUND OF THE INVENTION

Most insulation sheets and segments which are used presently either withpipes or duct work have an exterior coating of paper. For example, asshown in copending U.S. patent application Ser. No. 804,066 assigned tothe assignee herein, cylindrical insulation segments used with pipestypically comprise an inner, metallized layer, a layer of fiberglassyarn, and an outer, paper layer which is typically a kraft paper. Theouter layer frequently includes a scrim laminated between paper layerswhich produces a textured outer surface to the segment. Thesecylindrical segments extend along a pipe in an end to end abuttingrelationship. Also, each segment typically is slit along its length forinsertion of the pipe, and a proper flap is provided for covering theslit and for sealing the pipe within the segment. The undersurface ofthe flap is provided with a strip of a pressure sensitive adhesive toallow it to be secured to the outer paper layer of the segment. Thespaces between abutting ends of the segments may be sealed using a tapesuch as a butt strip tape, having a pressure sensitive adhesive. Thistape preferably has an outer paper layer, a middle layer of fiberglass,an inner metallized layer, and a ayer of a pressure sensitive adhesivedisposed on the metallized layer, as described in copending U.S. patentapplication Ser. No. 804,066. The tape is wrapped about the abuttingends of the segments so that one end of the tape overlaps the other endto seal the space between the segments.

Often, it is necessary to apply the strip of adhesive to theundersurface of the flap of the insulation segment at the job site. Inthis instance, the adhesive is provided on a roll using a double sidedrelease paper having a differential release, as descrbed in U.S. patentapplication Ser. No. 804,066. Therefore, if the undersurface of the flaphas moisture on it at the time of application of the adhesive strip, theadhesive may not bond well to the flap.

In each instance, for both the paper flap and the butt strip tape, theintegrity of the seal is a function of the strength of the bond betweena pressure sensitive adhesive and a layer of paper, whether it be thetape or the insulation segment. If the tape and flap are sealed in placewhen the paper layer is dry, and the paper layer never becomes dampthrough absorption of moisture, the integrity of the seal will bemaintained. However, more often than not, especially in newconstruction, insulation segments are used in basements or areas whichare exposed to the weather, where the outer paper layer absorbs moisturefrom the surrounding environment. Eventually, under such conditions, thepaper layer is likely to disintegrate, delaminate or even separate fromthe fiberglass layer. If this disintegration or delamination occurs, theintegrity of the seal between the butt strip tape and the segment orbetween the flap and the segment may be destroyed. Also, because of thetextured outer surface, if inadequate pressure is applied to the flap orthe tape, the pressure sensitive adhesive will adhere only to the raisedportions of the outer surface, which is less than 25% of the totalsurface area of the segment. Because of this inadequate bond,"fish-mouthing" is more likely and the bond between the butt strip tapeand the outer surface of the segment is less secure. With respect to theflap seal, such delamination or disintegration can allow the flap torise off the insulation segment to cause what is known as "fishmouthing". "Fish mouthing" can occur as a result of the breakdownbetween the adhesive strip and the flap or between the adhesive stripand the outer surface of the segment. Such delamination ordisintegration can occur over a period of a few weeks in very dampenvironments, or a period of many months in less damp environments.Eventually, the insulation segments must be removed and replaced if thedesired level of protection is to be maintained. "Fish mouthing" is aparticular problem on jobs for the U.S. Government, since such "fishmouthing" does not meet specifications for the U.S. Government, and thecontractor may be required to return to the site and repair the damageat his own cost.

Some manufacturers of cylindrical insulation segments provide them withan outer layer of plastic such as polyvinylchloride (PVC). Although thePVC does not delaminate, some difficulty may be experienced in securingeither the butt strip tape or the flap to the outer surface of thesegment if moisture is present. Also, acrylic adhesives are generallyused to seal the flap on the segment and to secure the butt strip tapeto the segment, and acrylic adhesives do not adhere well to PVC. Anyincomplete seal could result in "fish mouthing" of the flap or eventualfailure of the seal around the butt strip tape.

Fibrous duct board is often used for insulation of duct work,particularly square or rectanqular ducts. Such duct board is provided insomewhat rigid sheets. This duct board has a structure somewhat similarto that of the pipe insulation segments previously described andgenerally comprises an outer metallized layer, a middle layer offiberglass yarns, or mineral wool, and an inner paper layer which istypically a kraft paper. On some duct board products the paper is on theouter surface and the metallized layer is on the inner surface. Thefiberglass or mineral wool layer of the duct board is more tightlypacked than in the segments, thus providing it with the greaterrigidity. The duct board generally is cut to the size of the duct work,and the resulting sheets cover the surfaces of the duct work. Sheets areplaced in abutting relationship along each surface, and edges of thesheets on each surface adjoin edges of other sheets disposed onadjacent, perpendicular surfaces of the duct. A pressure sensitiveadhesive tape may be used to seal the spaces between abutting andadjoining edges of the duct board. The tape is secured either to theouter surface, either to a metallized layer or to a paper layer.Generally, for adjoining, perpendicular edges of the sheets of ductboard, one transverse edge of the tape is applied to an edge of a sheetalong one surface, and the tape is then folded along a line parallel toits length so that the other transverse edge of the tape is secured toan edge of a sheet of duct board disposed on an adjoining, perpendicularsurface. This fold in the tape occurs across the machine direction ofthe tape, and therefore the tape resists folding and tends to straightenitself out into its original, generally flat confiquration. As a result,a shear stress results between the tape and the outer surfaces,particularly along the adjoining edges between perpendicular sheets ofduct board.

The outer layer of such duct board is susceptible to damage resultingfrom moisture absorbed from the surrounding environment. If moisture ispresent either in the paper or on the metallized layer when the adhesivetape is applied, or if such moisture is absorbed by the paper at a latertime, the integrity of the seal can be compromised. As with the pipeinsulation, the paper layer can disintegrate or separate, thusdestroying the bond between the tape and the sheet of duct board.Because of the shear stresses along perpendicular junctions, once theouter layer begins to disintegrate or delaminate, the tape has atendency to pull free from one or the other of the edges of theperpendicularly disposed sheets of duct board, and this tendencyaccelerates the delamination or disintegration process. Eventually, theintegrity of the seal is destroyed. This process is accelerated if ascrim is laminated into the outer layer and the outer layer is textured,as described for the insulation segments. Again, if the duct work is tobe properly insulated, the tape, and often all of the the sheets of ductboard must be replaced.

Flexible blanket insulation is also used for insulation of duct work.Such blanket insulation typically is provided in long rolls from whichthe insulation is cut and wrapped about the duct work. The structure ofsuch blanket insulation has the same structure, in most instances, asthe previously described cylindrical insulation segments and duct board,and comprises an outer metalized layer, a middle layer of fiberglassyarns, which are loosely packed to be flexible, and an inner layer whichis typically a kraft paper. As described in copending U.S. patentapplication Ser. No. 905,701, filed Sept. 9, 1986, and assigned to theassignee of the present application, adjacent lateral edges of segmentsof blanket insulation cut from the roll are sealed to one another by theuse of strips of tape to effect a seal about the ducts. Again, the outerpaper layer of such blanket insulation is susceptible to damageresulting from moisture absorbed from the surrounding environment orfrom moisture which is already present in the paper when the tape isapplied. If disintegration or delamination of the paper layer occurs,the integrity of the seal could be destroyed if the tape pulls loose.

Again, this process would be accelerated if a scrim is used in the outerlayer to provide it with a textured surface. In addition, the tape usedto seal together the edges of such blanket insulation is secured in anend to end, overlapping relation. The structure of this tape issubstantially identical to that of the butt strip tape previouslydescribed, and contains an outer, paper layer. Therefore, if moisture ispresent in the paper layer of such tape, disintegration or delaminationagain could occur, thus destroying the seal created by the tape.

In each instance, the replacement of insulation after a very shortperiod of time is very expensive and results in additional buildingcosts. If the insulation is not replaced, the effectiveness of theinsulation is significantly reduced, and significant monetary lossesresult from the escape of heat from the pipes or duct work.

It is an object of this invention to provide a moisture proof surface oninsulation segments, sheets and blankets, and on tape used to seal suchinsulation segments, sheets and blankets at locations where a pressuresensitive adhesive tape is to be applied.

It is also an object of this invention to provide superior adhesivebonding surfaces upon which pressure sensitive adhesive tapes may beapplied for sealing pipe insulation segments together.

It is a further object of this invention to provide a superior adhesivebonding surface for the pressure sensitive adhesive layer of the flap ona pipe insulation segment.

It is a further object of the present invention to provide a superioradhesive bonding surface on ends of a butt strip tape used for sealingabutting ends of insulation segments on pipes.

It is a further object of the present invention to provide a superioradhesive bonding surface on the perimeter of sheets of duct board usedfor insulating ducts to permit secure attachment of pressure sensitiveadhesive tapes to the edges of the duct board for sealing abutting andadjoining edges to one another.

It is a further object of the present invention to provide a superioradhesive bonding surface on the lateral edges of rolls of blanketinsulation used for insulating ducts to permit secure attachment ofpressure sensitive adhesive tapes to the lateral edges of the blanketinsulation for sealing abutting and adjoining edges to one another.

It is a further object of the present invention to provide a superioradhesive bonding surface on ends of tape used to seal abutting andadjoining edges of blanket insulation to one another.

SUMMARY OF THE INVENTION

The foregoing and other objects of this invention are achieved by theprovision of strips of a water resistant, nontacky coating material onthe surfaces of the insulation and tapes at points where attachment of apressure sensitive adhesive is desired. The exact width of the stripsdepends upon the particular application, but generally should be alittle greater than the width of the portion of the adhesive which is tobe secured thereto. A three inch width is preferred, although the width,as indicated, can be greater or less than this amount. Preferably, thestrip of coating material is applied at the factory when the product ismanufactured. The particular coating material used should be one that ismoisture resistant, is nonblocking, and, when dried, one that allowspressure sensitive adhesive tapes to adhere readily to it. Also, thecoating material should remain flexible at high and low temperatures.The coating material is a cured adhesive system, preferably a linearsaturated polyester and polyisocyanate cured adhesive system.

A preferred linear saturated polyester and polyisocyanate adhesivesystem is a two component solvent based system using Bostik 7064 andBoscodur No. 40. The linear saturated polyester is mixed with thepolyisocyanate, blended, applied to the surface and allowed to cure.

With respect to cylindrical pipe insulation segments, a strip of thecoating material is applied adjacent the slit which extends axiallyalong the length of the isulation segment where the covering flap is tobe secured to the outer surface of the segment. In addition, otherstrips of the coating material can be disposed around the outercircumference of the segment adjacent each end thereof for attachment ofbutt strip tape thereto. Finally, if the adhesive layer is applied tothe flap on site, a strip of the coating material is deployed on theinside surface of the flap adjacent the outer edge.

The butt strip tape used to seal together abutting ends of the segmentsis preferably provided in strips of predetermined lengths, and not in aroll, and the strips are sized for the circumference of particular pipeinsulation segments. A strip of coating material is disposed at one endof each tape strip and spaced from the end, on the outer, nonadhesivesurface thereof, so that as the tape strip is wrapped about thecircumference of the pipe insulation segment, a strip of coatingmaterial is present at the point where the tape strip is adhered to theouter surface of itself.

This invention also has application to duct board and blanket insulationfor heating ducts. The outwardly facing, paper surface of the duct boardis provided with a strip of coating material along its outer edges andthis strip extends either around the entire perimeter thereof or on onlytwo sides thereof. The strip of coating material allows proper bondingof pressure sensitive adhesive tapes to seal the spaces between theedges of anqularly disposed sheets covering the duct, as well as thespaces between abutting ends of sheets disposed on one surface of theduct. The outwardly facing surface of the blanket insulation is providedwith a strip of coating material along its lateral edges. The width ofthe strip depends upon the width of the tape used, but is generallyabout two to three inches. Tapes used to seal the blanket insulationalso are provided in premeasured lengths and have a strip of coatingmaterial at one end on their outer surface.

The provision of such a strip of coating material on the insulationmaterial, and on the tapes, prepares the surface thereof so that it willadhere better to the pressure sensitive adhesive tape. The coatingmaterial saturates paper so that water cannot penetrate, thus renderingthis portion of the paper layer moisture resistant. The coating materialalso provides a smooth, flat surface to which the adhesive can bond,thus filling in any irreqularities on the surface caused by a scrim orthe like. The particular material selected is particularly advantageousbecause it is moisture resistant, flexible, will bond to adhesives, isabsorbed by paper, will stick to paper, PVC or a metallized surface,will not adhere to dirt, and has no static cling which will attract dustor other materials.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, advantages and features of this invention will be moreclearly appreciated from the following detailed description when takenin conjunction with the accompanying drawings in which:

FIG. 1 is a partially cut away, perspective view of a pipe insulationsegment showing one embodiment of this invention;

FIG. 2 is a perspective view of a pipe insulation segment showinganother embodiment of this invention in which the adhesive layer isapplied to the flap at the job site;

FIG. 3 is a cross sectional view of a cutaway portion of butt strip tapesegment illustrating another embodiment of this invention;

FIG. 4 is a partially cut away, perspective view of a pipe insulationsegment showing the butt strip tape of FIG. 3 used in conjunctiontherewith;

FIG. 5 is a top, planar view of the butt strip tape segment shown inFIG. 3;

FIG. 6 is a partially cut away perspective view showing anotherembodiment of this invention when used in conjunction with duct board;

FIG. 7 is a partially, cut away, exploded perspective view showing therelationship of the duct board illustrated in FIG. 6;

FIG. 8 is a cross sectional planar view taken along the lines 8--8 ofFIG. 6; and

FIG. 9 is a perspective view showing a roll of partially unrolledblanket insulation having a strip of coating material of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference now to the drawings, and more particularly to FIG. 1thereof, this invention first will be described with regard to oneembodiment thereof when used in conjunction with cylindrical, pipeinsulation segments. FIG. 1 shows a portion of an insulation segment 10installed around pipe 12. Pipe 12 may be any conventional hot or coldwater pipe or steam pipe or pipe for carrying chemicals or petroleumproducts. Pipe 12 can be formed of any conventional material, such ascopper, steel, plastic, aluminum or rubber. Segment 10 is comprised of aflame resistant, vapor barrier material. Segment 10 may have an outerlayer of a plastic material such as polyvinylchloride (PVC) (not shown)but segment 10 typically comprises an outer flame retardant paper layer16, a middle layer 17 of fiberglass yarns, and an inner metallized layer18. Typically, paper layer 16 and metallized layer 18 are secured toopposite sides of fiberglass layer 17 using a flame resistant laminatingadhesive. However, the metallized layer can also be disposed betweenpaper layer 16 and layer 17. In one embodiment, metallized layer 18 is alayer of aluminum foil, while in another embodiment, metallized layer 18is an aluminized polyester film.

Generally, although not always, paper layer 16 is a high intensity,white, chemically treated kraft paper, and the weight of the paper is inthe order of 45 pounds per 3000 square feet. Layer 16 may contain anembedded scrim which produces a textured outer surface which has araised pattern identical to the scrim pattern. Layer 17 typically,although not always, is comprised of fiberglass scrim yarns and has atridimensional 5×5 fiberglass construction. Segment 10 is split alongits entire length at slit 50, and slit 50 is adapted to be sealed alongits length by a flap 52. Flap 52 typically is an extension of paperlayer 16, or if layers 16 and 18 are laminated to form a single unit,flap 52 is an extension of the unit formed by layers 16 and 18.

As shown in FIG. 1, an adhesive strip 80 is provided on the undersurfaceof flap 52 for sealing of flap 52 to the outside surface of paper layer16 adjacent slit 50. Strip 80 extends the entire length of flap 52 andis covered with a layer of release paper 81 prior to sealing of theflap. Adhesive strip 80 typically is comprised of a pressure sensitiveadhesive, such as an isooctyl acrylate polymer, as described incopending U.S. patent application Ser. No. 804,066.

As previously described, in prior art insulation segments, paper layer16 has a tendency to absorb moisture from its environment, both beforeand after sealing of flap 52 thereto. Also, if segment 10 has an outerPVC coating, moisture tends to form on the surface thereof. In prior artsegments, if the outer layer is moist at the location adjacent slit 50,adhesive layer 80 is not tightly and optimally secured thereto. Inaddition, if absorption of moisture occurs after sealing of flap 52 tothe outside of segment 10, such moisture can cause layer 16 to begin todisintegrate or delaminate. Flap 52 has a natural tendency, because ofits method of manufacture, to tend to open up or lift off its point ofattachment. As layer 16 begins to disintegrate or delaminate, flap 52will rise off the insulation segment, or "fish mouth", taking a portionof layer 16 with it, thus providing an air gap through which heat canenter or escape. "Fish mouthing" is further accelerated if layer 16 hasa textured outer surface, because the adhesive may only bond to the 25%of the surface that is raised, if enough pressure is not applied to theadhesive. Also, if the outer surface of segment 10 is formed of PVC, thepresence of moisture can also cause flap 52 to "fish mouth."

In this embodiment of the invention, this "fish mouthing" problem isovercome by the provision of a strip 60 of a coating material whichextends along nearly the entire length of segment 10 and which isdisposed closely adjacent slit 50 on paper layer 16. Strip 60 typicallyhas a width sufficiently great that it extends to the outer edge 83 offlap 52 when flap 52 is folded over slit 50 and is secured to the outersurface of segments 10. Typically, this width is about one and one halfto about three inches. In this manner, adhesive layer 80 is securedalong its entire length only to strip 60. Strip 60 prepares the surfacefor the adhesive, and for a paper layer 16, the paper layer all the waydown to the laminating adhesive so that water cannot penetrate intolayer 16 at the point where flap 52 is secured. A smooth, flat surfaceis provided to which the adhesive can bond. In this manner, delaminationand disintegration of layer 16 adjacent flap 52 are eliminated.

The coating material used for strip 60 preferably is nonblocking whencured and is moisture resistant. Also, it may have the followingproperties: sufficiently flexible so as not to crack when bent orfolded; remains flexible within the range of temperatures from about150° F. to about -20° F.; of bonding to a pressure sensitive adhesivesuch as an isooctyl acrylate polymer; capable of being absorbed bypaper; capable of adhering to paper, a plastic material such as PVC andmetallized surfaces; not capable of adhering to dirt; transparent(although this is not an essential property); and no static cling so itwill not attract dust. Materials which can be used for strip 60 arecured, adhesive systems. The preferred material is prepared from acured, two component, solvent based linear, saturated polyester adhesivesystem.

Conventional gravure or flexographic equipment may be used forapplication of the coating material. In an alternative embodiment, apneumatically pressurized roller tip having a knurled surface can beused to apply the mix in a manner similar to that used with gravureequipment. An example of an acceptable pressurized roller is thatmanufactured by Aro Corporation, One Aro Center, Bryan, Ohio 43506,under Model No. 463122-3. Large knurling is used on the roller toprovide the desired amount of adhesive. Typically, the roller is about 3inches wide. The mixture may also be sprayed on the surface of paperlayer 16 using a conventional pneumatically driven spray system.Thereafter, the solution is fully cured to drive off all solvents untilthe resulting strip 60 is nonblocking. Typically, strip 60 is curedusing a conventional drying oven, such as an infrared oven provided withan air flow therethrough. The oven is maintained at a temperature in arange of from about 200° F. to about 250° F.

The following are a number of non-limiting illustrative examples ofcured adhesive systems which can be used as a coating material inaccordance with this invention:

EXAMPLE 1

A preferred coating material is prepared from a two component, solventbased adhesive system, in which the primary component comprises a linearsaturated polyester base and a toluol/methylene chloride solvent. Thisprimary component has about 27% total solids, a Brookfield viscosity of900 to 1100 CPS, and it has a specific gravity of about 1.1 kilogramsper liter. It is light straw in color. Its flash point is 66° F. Theother component of this system is a catalyst, and is preferably apolyfunctional aliphatic isocyanate resin dissolved in n-butylacetate/xylene (1:1). The specific gravity of the preferredpolyisocyanate compound is 1.06 kilograms per liter and containsapproximately 25%±2% volatiles by weight. Its NCO content is 16.5% to0.5% and the viscosity is 250 mpa's. The free HDI monomer weight of thecatalyst is 0.7% maximum, and the flash point is about 87° F. It is aclear, slightly yellow liquid. Suitable components may be purchasedcommercially from Bostik Chemical Division of the Emhart Fastener Group,Boston Street, Middleton, Mass. 01949. A suitable primary component isBostik 7064, and a suitable catalyst is Boscodur No. 40.

When preparing the coating material for use, the primary component, suchas the Bostik 7064, is diluted with methylene chloride ortrichlorylethylene until it has a solids content of in the range of fromabout 28% to 38% by weight. A premix is then formed with the primarycomponent and the catalyst. The primary component constitutes about fourparts by volume of the premix, and the catalyst comprises about one partby volume of the premix. This premix is then blended in a known manner,such as by a lightening mixer, until a homogeneous solution is obtained,or until the polyisocyanate is totally in solution. Thereafter, thishomogeneous solution is applied wet to the surface of paper layer 16 andcured, all as described above, to form strip 60. Preferably, thesolution is applied wet in sufficient amounts so that it will have a drythickness in the range of from about 1.5 mils to 3.0 mils, and a drycoating weight in the range of from about 1.188 dry ounces per squareyard to about 2.376 dry ounces per square yard.

Shear tests were performed in which a strip of material coated with anadhesive, such as an isooctyl acrylate polymer was secured to a materialsuch as that comprising a segment 10 having an outer paper layer 16. Onetest was performed in which the paper layer was uncoated, and anothertest was performed in which the paper layer was coated with the curedlinear saturated polyester material described herein. A 1 kilogramweight was applied in shear (at an angle of about 180° to the surface ofpaper layer 16) both to the flaps secured to the coated layer and to theuncoated layer. In each instance, the weight was allowed to be suspendedfor a 15 minute period at room temperature (70° F.) and then thetemperature was elevated to first 100° F., then 150° F., and then 200°F. In this test, where no coating was present, the bond failed after 13hours. For the coated paper, the bond held after 24 hours. When thetemperature was raised to 150° F., the bond still held for an additional72 hours. Finally, when the temperature was raised to 200° F., the bondcontinued to hold for an additional 110 hours, at which point the testwas stopped. The same test was repetted using a 2 kilogram weight inshear. With a 2 kilogram weight, the flap secured to the paper having nocoating failed after 6 miutes at room temperature. With respect to thebond using a coating, after 1 hour at room temperature, there was nofailure. When the temperature was raised to 100° F., the bond onlyfailed after 27 hours.

EXAMPLE 2

Another acceptable coating material can be prepared from a twocomponent, solvent based adhesive system in which the primary componentagain comprises a linear saturated polyester base and chlorinatedsolvents. The total solids content of this primary component is higherthan that set forth in Example 1, and is 36%, ±1. The Brookfieldviscosity is 3500 CPS±500, and the specific gravity is about 10.72pounds per gallon (1:29 kilograms per liter). The primary component hasno flash point, and is light straw in color. The other component of thesystem is a catalyst, which is the same catalyst set forth in Example 1.Again, this catalyst is a polyfunctional aliphatic isocyanate resindissolved in n-butyl acetate-xylene (1:1). Suitable components may bepurchased commercially from Bostik Chemical Division of the EmhartFastener Group, Boston Street, Middleton, Mass. 01949. A suitable baseis Bostik 7205, and a suitable catalyst is Boscodur No. 40. Whenpreparing the coating material for use, a premix is formed in which theprimary component constitutes about 20 parts by volume and the catalystconstitutes about one part by volume. In all other respects, thiscoating material is prepared for use and applied in the same manner asset forth in Example 1.

EXAMPLE 3

Another acceptable coating material can be prepared from a twocomponent, solvent based adhesive system in which the primary componentcomprises a polyester resin base and methylethylketone and toluolsolvents. The primary component has about 43% to 47% total solids, and aBrookfield viscosity of 1000 to 2000 CPS. The primary component has aspecific gravity of about 7.95 pounds per gallon (0.95 kilograms perliter), and is light amber in color. The flash point of the primarycomponent is about 18° F. The other component of this system is acatalyst, and is preferably a polyfunctional aliphatic isocyanate resindissolved in n-butyl acetate/xylene (1:1). This catalyst is identical tothat set forth in Example 1. Suitable components may be purchasedcommercially from Bostik Chemical Division of the Emhart Fastener Group,Boston Street, Middleton, Mass. 01949. A suitable base is Bostik 7237,and a suitable catalyst is Boscodur No. 40. The primary component ismixed with the catalyst in a ratio of about 20 parts by volume to 1 partby volume for the primary component for the catalyst. In all otherrespects, this coating material is prepared for use and applied in thesame manner as set forth in Example 1.

EXAMPLE 4

Another coating material can be prepared from a two component, solventbased adhesive system in which the primary component comprises apolyester resin base and a methylethylketone solvent. This primarycomponent has about 70% ±1 total solids, a Brookfield viscosity of 3000CPS±1000 CPS and a specific gravity of about 9 pounds per gallon. Theflash point of the primary component is 16° F. The other component ofthis system is a catalyst, and is preferably a polyfunctional aliphaticisocyanate resin dissolved in n-butyl acetate/xylene (1:1). Thiscatalyst is identical to that set forth in Example 1. Suitablecomponents may be purchased commercially from Bostik Chemical Divisionof the Emhart Fastener Group, Boston Street, Middleton, Mass. 01949. Asuitable base is Boslam 7885, and a suitable catalyst is Boscodur No.40. This primary component is mixed with the catalyst so that thecatalyst comprises approximately 10% to 12% of the total mix by weight.In all other respects, this coating material is prepared for use andapplied in the same manner as set forth in Example 1.

EXAMPLE 5

Another coating material can be prepared from a single component,solvent based adhesive which comprises a urethane base and amethylethylketone/toluol solvent. This adhesive has about 20% ±1 totalsolids, a Brookfield viscosity of about 5 to 600 CPS and a specificgravity of 7.3 pounds per gallon (0.87 kilograms per liter). Theadhesive is clear in color, has a medium syrup consistency, and has aflash point of about 35° F. A suitable adhesive may be purchasedcommercially from Bostik Chemical Division of the Emhart Fastener Group,under the product designation Bostik 7376. In all other respects, thiscoating material is prepared for use and applied in the same manner asset forth in Example 1.

EXAMPLE 6

Another coating material can be prepared from a single component,solvent based adhesive which comprises a vinyl base carried in a solventcomprising about 91% methylethylketone and about 9% toluene. Thisadhesive has about 35% total solids, a Brookfield viscosity of about1000 CPS and a specific gravity of 7.8 pounds per gallon. This adhesivehas a flash point of about 20° F., and an appearance which is clear andstraw-colored as a liquid, but colorless as a film. A suitable adhesivemay be purchased from National Starch And Chemical Corporation, TheAdhesives Division, Finderne Avenue, P.0. Box 6500, Bridgewater, N.J.08807, under the product designation Duro-flex 30 1278. In all otherrespects, this coating material is prepared for use and applied in thesame manner as set forth in Example 1.

As shown in FIG. 2, in some applications, it is necessary to applyadhesive layer 80 to flap 52 at the job site, rather than at thefactory. In such an instance, the layer of adhesive is provided in aroll and secured to a conventional silicone coated release paper 122having differential release characteristics. A strip of such releasepaper 122 can be cut from the roll at the job site and applied asillustrated in FIG. 2. The side of release paper 122 having the easyrelease is disposed so as to face upwardly away from flap 52, while theside of release paper 122 having a tighter release retains the adhesivelayer which is applied to flap 52. Thereafter, when it is desired toseal flap 52 to strip 60 on segment 10, release paper 122 can be removedfrom flap 52, leaving behind adhesive layer 80 secured directly to flap52 and exposed for application to strip 60.

In such applications, it is desirable to provide the undersurface offlap 52 with a strip 120 of a coating material for attachment of releasepaper 122 and adhesive layer 80 thereto. Strip 120 extends along theentire length of flap 52 from one end of segment 10 to the other end.The width of strip 120 is in the range of from about 11/2 inches toabout 3 inches. Typically, the strip of width 120 is about the same asthe width of strip 60 and extends to the outer edge 83 of flap 52. Strip120 is formed of the same material as is strip 60, preferably, a linearsaturated polyester, and it is applied in the same manner as strip 60.The same requirements which apply to strip 60 also apply to strip 120.This embodiment overcomes problems associated with the tendency of theundersurface of flap 52 to absorb moisture from its environment bothbefore and after sealing of flap 52 to the outside surface of paperlayer 16 adjacent slit 50, and associated with a textured surface. Aspreviously described with regard to strip 60, the use of strip 122prevents "fish mouthing" which could result from disintegration of flap52 on its underside where adhesive layer 80 is secured thereto.

Segment 10 often is used with a plurality of other such segments toinsulate a pipe along its length. Exemplary segments 10 and 14 are shownin abutting relationship in FIG. 4 for a section of pipe 12. Segments 10and 14 abut one another at respective ends 22 and 24. The space betweenends 22 and 24 typically is sealed by butt strip tape 20 which iswrapped about the circumference of segments 10 and 14 and which issecured to itself by overlapping end 17 with end 19.

In prior art pipe insulation segments, the sealing of abutting ends ofinsulation segments 10 and 14 using tape 20 is subject to the samedifficulties and drawbacks as found in the proper sealing of flap 52.Namely, if paper layer 16 is used, it tends to disintegrate ordelaminate if moisture is absorbed, thus destroying the integrity of theseal. If a scrim is present, a poor seal may result. If a PVC coating isprovided on the outer surface of segment 10, moisture present can alsodestroy the integrity of the seal between tape 20 and segment 10. Aswith flap 50, these problems are overcome by the provision of a strip 62of coating material at each end of insulation segments 10 and 14. Strip62 typically extends from respective ends 22 and 24 of segments 10 and14 inwardly a prescribed distance towards the center of the segments.Strip 62 extends around the entire circumference of segments 10 and 14,including the outer surface of flap 52. The actual width of strip 62 isa function of the width of tape 20, and typically, strip 62 has a widthof about two or three inches. Strip 62 is formed of the same materialand is applied in the same manner as is strip 60.

A preferred embodiment of butt strip tape 20 is shown in FIGS. 3 through5. Butt strip tape 20 usually has a structure which is similar to thatof segments 10 and 14 so as to be compatible therewith, except that tape20 includes a thinner fiberglass layer. However, it is not necessarythat tape 20 have the same identical structure as segments 10 and 14 andother structures are possible. In the preferred embodiment, as shown inFIG. 3, tape 20 includes a layer 26 of paper, a layer 28 of fiberglass,a metallized layer 30, a layer 32 of a pressure sensitive adhesive, anda layer 54 of release paper. Often, paper layer 26 contains a fiberglassscrim, providing the tape with a textured surface having a raisedpattern in accordance with the scrim pattern. Paper layer 26 andfiberglass layer 28 are secured together using laminating adhesive 34,while fiberglass layer 28 and metallized layer 30 are secured togetherby laminating adhesive 36. Paper layer 26 again is preferably a highintensity, white, chemically treated kraft paper which is flameretardant. Fiberglass layer 28 is made of fiberglass yarns, andtypically is woven to form either a tridirectional or diamond patternedweave, or a scrim having a square weave such as a 5×5 scrim. Laminatingadhesives 34 and 36 can be any conventional, thermo-setting,flame-retardant adhesives which are suitable for laminating fiberglassto paper and to polyester or metal. Layer 30 can be either a layer ofaluminum foil, or a layer of a metallized polyester film. Typically, ifa metallized polyester film is used, the metal deposited thereon isaluminum. Release paper 54 can be any conventional release paper whichis suitable for use with an acrylic adhesive. The adhesive layertypically is an isooctyl, acrylate polymer adhesive, as described incopending U.S. patent application Ser. No. 804,066.

As illustrated in FIG. 4 and as previously described, when tape 20 isapplied to abutting ends 22 and 24 of segments 10 and 14 respectively,one end 17 of tape 20 is secured directly to the outer surface ofsegments 10 and 14, while the other end 19 of tape 20 overlaps end 17and is secured to the top surface of tape 20. Paper layer 26 is subjectto the same raised surface, disintegration delamination problems aspaper layer 16 of segment 10 where end 19 is sealed to end 17. Again,this poses a threat to the integrity of the seal.

The foregoing problem is overcome by the embodiment of the butt striptape 20 shown in FIGS. 3 through 5. In this embodiment of the invention,butt strip tape 20 is provided in segments of a premeasured length,which is a function of the circumference of segment 10 with which tape20 is to be used. The circumference of segment 10 is in turn a functionof the diameter of pipe 12 and of the desired thickness of layer 17.Adjacent one end of each segment of tape 20, a strip 66 of a coatingmaterial is provided on the outer surface of paper layer 26. Strip 66preferably is spaced about 1 inch from the end of the tape segmentalthough it could also extend up to the end of the tape segment. Strip66 is formed of the same material as strips 60 and 62, preferably alinear saturated polyester, and strip 66 may be applied in the samemanner. Preferably, the tape is formed in a continuous length, and anintermittant spray system is used to apply the coating at the properintervals and widths along its length. The length of tape is later cutinto appropriate segments. Strip 66 can be of any width, but typicallystrip 66 has a width of about two or three inches. Strip 66 is providedon an end of a segment of tape 20 which is to be directly secured to theouter surface of segments 10 and 14.

Another embodiment of the present invention will be described withparticular reference to FIGS. 6-8. This embodiment of the invention isshown for use with duct board employed for insulating heating ducts andother similar duct work. Duct board is provided in flat, generally rigidsheets, and typically has a structure as shown in FIG. 8 which issimilar to the structure of pipe segment 10 shown in FIG. 1. Duct board70 typically comprises a flame retardant paper layer 72, a layer 76 offiberglass yarns, and a metallized layer 74. Typically, the paper layerand the metallized layer are secured to opposite sides of the fiberglasslayer 76 with a flame resistant laminating adhesive. Fiberglass layer 76is formed of a high density fiberglass wool and provides duct board 70with its desired rigidity. During installation of duct board 70 on atypical duct 78, as shown in FIG. 6, metallized layer 74 generally ispositioned to be on the outside surface facing away from duct 78.

FIG. 6 shows the use of duct board 70 in conjunction with a typical duct78 having a rectanqular cross section. With regard to duct 78, top andbottom panels 88 and side panels 86 of duct board 78 are provided.Panels 88 and 86 are trimmed to the appropriate size for use inconjunction with duct 78. Side edge 90 of panel 88 adjoins and is sealedto side edge 92 of panel 86 to provide the desired seal about duct 78.In a typical installation, as shown in FIG. 7, edge 90 of panel 88overlaps edge 92 of panel 86 so that layer 76 of panel 88 remainsexposed.

Tape 94 is used to seal together edges 90 and 92. Tape 94 is generallyapplied from a roll and tape 94 extends in its lengthwise directionalong and parallel to edges 90 and 92. This particular application ofthe tape requires that the tape be creased or folded in its direction ofelongation as shown in FIG. 8 so that one half is disposed on edge 90,while another portion thereof is secured to edge 92. Because of itsmethod of manufacture, when folded in this lengthwise direction, tape 94is less flexible than when folded in its transverse direction. This isbecause a lengthwise fold is transverse to the machine direction of thetape. As a result, the tape has a tendency to try to retain its originalflat condition. When tape 94 is applied, a shear stress thus resultsalong edges 90 and 92 between the tape and the insulation surface towhich it is secured.

Metallized layer 74 may collect water by condensation or by directapplication before application of tape 94 thereto. As a consequence thebond between tape 94 and layer 74 is weak. Because of the shear stressbetween tape 94 and paper layer 74, tape 94 has a tendency to releasefrom either edge 90 or edge 92. As a result, a seal is difficult tomaintain, especially in humid conditions, and the tape and insulationpanels frequently have to be replaced. This problem is aggravated by thefact that the duct board is almost always left in an exposed situation,and frequently is found in basements or other locations where themoisture content of the air is high.

The foregoing problem is overcome by the provision of a strip 96 ofcoating material disposed on metallized layer 74 along the lateral edgesof panel 86, and a similar strip 98 of coating material disposed onmetallized layer 74 along the lateral edges of panel 88. Strips 96 and98 are formed of the same material as are strips 60 and 62 of segment10, which is preferably a linear saturated polyester. Strips 96 and 98are also applied in the same manner as are strips 60 and 62. Ideally,the width of strips 96 and 98 is sufficient to accommodate the entirewidth of tape 94 when used in the arrangement shown in FIG. 8. A typicalwidth is two to three inches.

Tape 94 is also used to seal the spaces between abutting longitudinalends 99 of panels 86 and 88. Tape 94 typically is wrapped all the wayaround the perimeter of duct 78. Although the tendency for the tape tocome loose at such a joint is not as great as along edges 90 and 92,because the tape is folded only transversely or parallel to the machinedirection, a poor bond due to dirt or moisture may still allow tape 94to eventually release from the surface of panels 86 and 88. Therefore,in an alternative embodiment, a strip 100 of coating material isprovided along the edge of each longitudinal end 99 of each panel 86 and88. Strips 100 are formed of the same material and applied in the samemanner as are strips 96 and 98.

The provision of strips 96, 98 and 100 along the edges of side andlongitudinal ends respectively of duct board panels 86 and 88 allow thepanels to be firmly and tightly sealed to one another at their edgesusing tape, and permit the creation of a high integrity seal about duct78. The integrity of this seal will not be compromised by moisture ordirt, and the seal should last as long as the insulation panels 86 and88. As a result, there is no need for frequent replacement of panels 86and 88.

A further embodiment of the present invention will be described withparticular reference to FIG. 9. This embodiment of the invention isshown in conjunction with a blanket insulation 126 which is employed forinsulating heating ducts and other similar duct work. Blanket insulation126 is provided in rolls, and is generally highly flexible. Blanketinsulation 126 typically has the same structure as duct board, as shownin FIG. 8 and typically comprises a flame retardant paper layer 128, alayer of loosely woven fiberglass yarns 130, and a metallized layer 132.Typically, the paper layer and the metallized layer are secured toopposite sides of fiberglass layer 130 with a flame resistant laminatingadhesive. However, metallized layer 132 may be disposed between paperlayer 128 and fiberglass layer 130. Fiberglass layer 130 is formed of alow density fiberglass wool and allows blanket insulation 126 to havethe desired flexibility. During installation of blanket insulation 126on a typical duct (not shown), either paper layer 128 or metallizedlayer 132 may be positioned to be on the outside surface facing awayfrom the duct.

During the installation of typical blanket insulation, as described inU.S. patent application Ser. No. 905,701, filed Sept. 9, 1986, andassigned to the assignee of the present application, lateral edges ofthe blanket insulation are placed in side by side relation along a ductand are secured together using segments of tape, such as those shown inFIGS. 3-5. This seal is subject to compromise because of moisture ordirt, as previously described for similar insulation structures. Thisproblem is overcome by providing a strip 134 of a coating material alongthe lateral edges of the entire roll of blanket insulation 126 either onpaper layer 128 or on metallized layer 132. This strip 134 of a coatingmaterial has the same composition as strip 60, and is applied in thesame manner.

The tape segments used to seal edges 136 of adjoining segments ofblanket insulation typically overlap one another in an end to endrelation. Therefore, tape segments having a layer of a coating materialat one end on the paper layer, such as those shown in FIGS. 3-5, arepreferably used, so that the overlapping portions of the segments aresecured tightly to one another, and do not suffer from the problems ofdelamination and disintegration of the paper layer.

The linear saturated polyester material used for forming the strips oneach of the embodiments of this invention is ideally suited for such ause because it contains all of the required properties. It is moistureresistant, flexible, flexible at high or low temperatures, it will bondto pressure sensitive adhesives, it is absorbed by paper, it will adhereto paper, PVC or a metallized surface, it is clear, it has no staticcling, and it does not remain sticky once it has been cured, and itprovides a flat, smooth surface to which an adhesive will bond over itsentire surface.

This invention overcomes serious problems with the use of tape systemsin pipe and duct insulation applications. This invention allows thecreation of a seal of high integrity which need not be repaired orreplaced for long periods of time and which meets existing U.S.Government specifications.

Modifications and improvements will occur within the scope of thisinvention to those skilled in the art, and the above description isintended as exemplary only. The scope of this invention is defined onlyby the following claims and their equivalents.

What is claimed is:
 1. An insulation system for an elongated fluidconduit comprising:means for insulating the elongated fluid conduit,said insulating means comprising an insulating layer and an outwardlyfacing top layer, said insulating means having a slit defined by a pairof spaced, parallel, confronting edges; a first strip of a waterresistant, nontacky coating material disposed on said top layer closelyadjacent at least one of said two edges defining said slit and extendingthe length of said slit; and means having a pressure sensitive adhesivethereon for sealing said slit, the adhesive of said sealing means beingadhesively bonded to said first strip of coating material adjacent saidone of said edges, said sealing means extending across said slit to theother of said edges.
 2. An insulation system as recited in claim 1wherein said insulating means comprises a generally cylindrical segmentfor covering the conduit, and wherein said slit extends lengthwisegenerally in the direction of elongation of the conduit.
 3. Aninsulation system as recited in claim 2 wherein said sealing meanscomprises a flap formed as an extension of said top layer extending fromsaid other of said edges.
 4. An insulation system as recited in claim 3further comprising a second strip of a water resistant, nontacky coatingmaterial disposed on the undersurface of said flap in confrontingrelation with said strip of coating material disposed adjacent saidslit, said second strip having a layer of a pressure sensitive adhesivedisposed thereon.
 5. An insulation system as recited in claim 1 furthercomprising a third strip of a water resistant, nontacky coating materialdisposed on said top layer closely adjacent to said other of said edgesand extending the length of said slit, wherein said insulating meanscomprises two generally cylindrical insulation segments having abuttingends for covering the conduit, wherein said pair of edges is formed onsaid abutting ends of said segments, wherein said slit extends generallytransverse to the direction of elongation of the conduit, and whereinsaid sealing means comprises a pressure sensitive adhesive tape securedto said first and said third strips of coating material adjacent saidone and said other of said edges respectively.
 6. An insulation systemas recited in claim 5 wherein said pressure sensitive adhesive tapecomprises a tape segment of a predetermined length, said tape segmentcomprising:a first nonadhesive side; a second side having a pressuresensitive adhesive disposed thereon; and a strip of a coating materialdisposed adjacent one end of said tape segment on said first sidethereof, said tape segment being wrapped about said insulation segmentsso that said second side of said tape segment is secured to said stripon said one end of said tape segment.
 7. An insulation system as recitedin claim 1 wherein said insulating means comprises a pair of generallyplanar panels disposed at an angle with respect to one another, andwherein one of said edges is disposed on one of said panels and theother of said edges is disposed on the other of said panels and whereinsaid sealing means comprises a pressure sensitive adhesive tape securedto said one and said other of said edges.
 8. An insulation system asrecited in claim 1 wherein said insulating means comprise a pair ofabutting panels disposed in generally the same plane and wherein saidpair of edges are disposed on abutting ends of said pair of panels, andwherein said sealing means comprises a pressure sensitive adhesive tapesecured to said one and said other of said edges.
 9. An insulationsystem as recited in claim 1 wherein said insulating means comprisesflexible, blanket insulation which is adapted to be wrapped about thefluid conduit.
 10. An insulation system as recited in claim 1 whereinsaid coating material comprises a cured adhesive system.
 11. Aninsulation system as recited in claim 10 wherein said adhesive has a drythickness in the range of from about 1.5 to 3.0 mils and a dry coatingweight in the range of from about 1.188 to about 2.376 dry ounces persquare yard.
 12. An insulation system as recited in claim 1 wherein saidstrip of coating material comprises a cured, linear saturated polyesteradhesive.
 13. An insulation system as recited in claim 12 wherein saidlinear saturated polyester adhesive is formed from two components,including a linear saturated polyester carried in a solvent and apolyisocyanate catalyst.
 14. An insulation system for a pipecomprising:an elongated cylindrical segment of an insulating materialfor being wrapped about the pipe; a centrally disposed channel extendingalong the length of said segment in the direction of elongation of saidsegment, said channel being adapted to receive the pipe therein; a slitextending along the length of said segment from an outer surface thereofto said central channel for allowing a pipe to be inserted into saidcentral channel; a flap disposed on said segment for sealing said slit,said flap having a layer of a pressure sensitive adhesive disposed on aninside surface thereof adapted to be secured to an outside surface ofsaid segment; and a strip of a water resistant, nontacky coatingmaterial disposed adjacent said slit on an outside surface of saidsegment and adapted to receive said adhesive layer of said flap.
 15. Aninsulation system as recited in claim 14 further comprising a strip of acoating material disposed between said inside surface of said flap andsaid layer of pressure sensitive adhesive disposed thereon.
 16. Aninsulation system as recited in claim 14 wherein said elongated segmentcomprises a first end and a second end spaced from one another in thedirection of elongation of said segment, and wherein said first end andsaid second end each are provided with a strip of a water resistant,nontacky coating material, said strip extending around substantially theentire circumference of said segment on the outer surface thereof inclosely spaced relation with said end.
 17. An insulation system asrecited in claim 14 wherein said strip of coating material comprises acured adhesive.
 18. An insulation system as recited in claim 16 whereinsaid strip of coating material comprises a cured adhesive.
 19. Aninsulation system for a pipe comprising:a first cylindrical segment ofinsulation for being wrapped about a pipe, said first segment having afirst end; a second cylindrical segment of insulation for being wrappedabout a pipe, said second segment of insulation having a first endadjacent to and closely abutting with said first end of said firstsegment to define a space therebetween; a first strip of a waterresistant, nontacky coating material disposed about the outercircumference of said first segment and positioned closely adjacent saidfirst end thereof; a second strip of a water resistant, nontacky coatingmaterial disposed about the outer circumference of said second segmentand positioned closely adjacent said first end thereof; and a pressuresensitive adhesive tape for sealing the space between said first end ofsaid first segment and said first end of said second segment, said tapebeing secured to said first and second strips of coating material onsaid first and second segments, respectively.
 20. An insulation systemas recited in claim 19, wherein each of said first and said secondstrips of coating material each comprise a cured adhesive.
 21. Aninsulation system as recited in claim 19, wherein said adhesive tapecomprises:an inner surface having a pressure sensitive adhesive disposedthereon; an outer surface; a strip of a water resistant, nontackycoating material disposed on said outer surface adjacent one endthereof, said one end being adapted to be overlapped by said innersurface at an opposite end thereof.
 22. An insulation system for a ducthaving a generally rectanqular cross sectional shape, said systemcomprising:a first insulation panel positioned along one surface of saidduct and having a first edge and an outwardly facing surface; a secondinsulation panel positioned along another surface of said duct disposedadjacent and generally normal to said one surface, said second panelhaving an outwardly facing surface and having a second edge disposedadjacent to and parallel to said first edge of said first panel todefine a space therebetween; two strips of a water resistant, nontackycoating material, one strip being disposed adjacent said first edge andthe other strip being disposed adjacent said second edge on theoutwardly facing surfaces of said respective first and second panels;and a pressure sensitive adhesive tape for securing said first edge tosaid second edge, said tape being secured to said strips of coatingmaterial.
 23. An insulation system as recited in claim 22 furthercomprising:a third insulation panel being disposed generally in the sameplane as a selected one of said first and said second insulation panels,said third insulation panel having an outwardly facing surface and athird edge abutting a transverse edge of said selected one of said firstand said second insulation panels; a first strip of a water resistant,nontacky coating material disposed on said outwardly facing surface ofsaid third insulation panel closely adjacent said third edge; a secondstrip of a water resistant, nontacky coating material disposed on saidoutwardly facing surface of said selected one of said first and secondinsulation panels closely adjacent said transverse edge thereof; and astrip of a pressure sensitive adhesive tape for sealing together saidtransverse edge and said third edge, said pressure sensitive adhesivetape being secured to said first and said second strips.
 24. Aninsulation system as recited in claim 23 wherein each of said stripscomprises a cured adhesive.
 25. Insulation for use in insulating a fluidconduit comprising:an outer layer; an inner layer of insulationmaterial; a pair of opposed edges; a strip of a water resistant,nontacky coating material disposed on said outer layer closely adjacentand parallel to each said edge, each strip extending along the length ofits associated edge; and means having a pressure sensitive adhesivethereon for sealing a space between said edges, said sealing means beingadhesively bonded to said strips of coating material adjacent saidedges.
 26. A segment as recited in claim 25 wherein each said strip iscomprised of a cured adhesive.